Possible Clues:

• Outer layer of disintegrating comet flipping hot inside?
• Doc with meter reviewed layer of embryo
• Outer layer of an embryo, which develops to form skin and nerves
• Outer skin layer
• Special therapy with flower balm's ultimate as basis of skin
• The outer germ layer of an animal embryo
• Outer germ layer that develops into skin
• External germinal layer of an embryo
• Fix up form of cermet outside as outer layer
• City name covering majority of untypical outer part